Comprehensive control of acariasis in foxes and mite

Acariasis is a chronic parasitic skin disease caused by mites belonging to the family scabies and acaridae parasitic on the body surface or under the epidermis of fur animals. For contact infection, if the feeding management is improper and the treatment is not timely, it will directly affect the animal health and fur quality, and cause serious losses to the farm.

In recent years, with the increase of the number and density of foxes and raccoons, the incidence of acariasis in foxes and raccoons is also increasing, and even foxes and raccoons in some farms often die of acariasis.

1 pathogen

Mites are incomplete arthropods, and their development includes four stages: egg, larva, nymph and adult.

1.1 scabies mites drill into the host epidermis and dig tunnels, and the worms develop and reproduce in the tunnel. At a considerable distance in the tunnel, there are small holes communicating with the outside world to pass through the air and serve as a channel for larvae to enter and exit. The female lays eggs in the tunnel, and each female can lay 40-50 eggs in a lifetime. After 2-3 days, the larvae hatch from the eggs, and the larvae climb to the surface of the skin, dig small holes in the skin between the hairs, transform into nymphs inside, drill into the skin, and form narrow and small caverns, where they are transformed into adults.

1.2 the female body of itch mite is oval and dirty white. The female produces dozens to 100 eggs, and under suitable conditions, 6-legged larvae are hatched in 3-4 days. After several days of molting, the larvae become terminal nymphs, and then molt into adults.

2 epidemic characteristics

Foxes and raccoons spread to each other through direct or indirect contact. Diseased animals are the main source of infection, such as intensive breeding, mating and so on. It can also be transmitted indirectly through directly contaminated cages, food basins, production boxes, overalls and gloves. In autumn and winter, lack of light, high temperature and humidity, and poor ventilation are conducive to the development of mites, so acariasis spreads widely and the disease is more serious. In late spring and early summer, the hair of the animal was changed, the ventilation was improved, the skin was exposed to sufficient light, and a large number of scabies mites and itch mites died, and the symptoms were relieved or completely recovered.

3Clinical symptoms

3.1 severe itching of scabies mites is the main symptom of the disease and runs through the whole disease. It usually occurs in the skin of the soles of the feet, then gradually spreads to the hocks and elbows, then spreads to the head, tail, neck and medial side of the chest and abdomen, and finally develops into systemic infection. The more severe the infection, the more severe the itch. Its characteristic is that the sick fox and raccoon dog enter the warm chamber or after exercise, the itch is more intense, making it constantly licking, scratching and rubbing against the surrounding objects, thus aggravating the inflammation of the affected part and spreading a large number of pathogens around. Foxes and raccoons suffer from extensive skin damage, loss of appetite and sometimes death from poisoning, but most of the diseases have a good prognosis after treatment.

3.2 in the initial stage, the local skin of the ear itch mite is inflamed, with a slight itch sensation, the diseased fox shakes its head from time to time, or rub the floor, chamber, cage net with the ear shell, and scratch the affected part with its claws, causing redness and swelling of the skin of the external auditory canal, forming inflammatory blisters and serous exudation. The exudate adheres to the hair on the lower edge of the ear shell and forms a scab after drying up, which is thickly embedded in the ear canal, such as paper roll, blocking the ear canal. Sometimes the ear itch mite drills into the inner ear, injures the tympanic membrane and causes the tympanic membrane to perforate. at this time, the diseased fox and the mite have a decreased appetite and the head turns to one side of the diseased ear at an angle of 90 °to 120 °. Severe cases may extend to the ethmoid bone and brain, resulting in spasm or epilepsy.

4 diagnosis

The disease is easy to be diagnosed according to the characteristic clinical symptoms (scab) caused by mite infestation on the affected animal skin. For diseased animals whose symptoms are not obvious, the crusts on the affected skin need to be collected and checked for mites before they can be diagnosed. In the conditional farm, scrape a little dirt under the scab with a surgical blade, put it in a clean glass dish, soak it with 10%NaOH solution for 3 minutes for 5 minutes, then dip a drop of suspension on the glass slide and observe it under a low power microscope, you can see mites in the visual field. Mites can also be observed with a magnifying glass with large magnification.

Inflammation differentiation: clinical should be different from mycosis, the main differences are: acariasis can be infected all over the body, sick animals have intense itching sensation, the appearance except depilation, the shape of the diseased part is irregular; fungal infection itching is slight, most of the diseased parts are round ringworm spots with obvious boundaries, the scab is backward and shows bright red and moist, the surface is eroded and with residual hair. If the sick materials are collected and examined by microscope after treatment, it is easier to distinguish between the two.

5 Prevention and control measures

Mites have a high degree of contagion, omission of affected parts, scattered disease materials, can cause new infection. The following measures can be taken for treatment.

Scab removal in order to make the drug fully contact with the insect body, cut off the coat on the affected area and the surrounding 3~4cm, collect the coat and dander in the dirt tube, burn or soak with acaricide, rinse with warm soap water to remove the hard scab and dirt.

5.2 repeated treatment of acariasis has no killing effect on mite eggs; therefore, it should be treated once every 5-7 days after treatment, in order to kill the newly hatched larvae and achieve the purpose of thorough treatment.

5.3 there are many drugs for the treatment of acariasis, some of which have been discontinued. Several commonly used drugs are introduced.

5.3.1 Ivermectin or avermectin is generally injected subcutaneously per kilogram of body weight according to 0.02mL neck, once every 7 days, 3 times in a row can be cured. However, in recent years, from the perspective of therapeutic effect, foxes and raccoons have a tendency to produce resistance to the above two drugs. Therefore, the dose can be slightly increased, for example, according to the use of 0.03~0.04mL per kg body weight, once every 5 days, the effect is more significant.

5.3.2 Tongmei is produced by Pfizer and is the drug of choice. The drug is more effective than ivermectin and avermectin in the treatment of acariasis, and its toxicity is less. It can be cured by using it once or twice.

5.3.3 according to other data, it was reported that the effect was obvious when treated with mirex or diazepam, which was cured after 1 or 2 times of treatment, but it was only suitable for small area infection. Specific method of operation: Baoding, which was diagnosed as suffering from acariasis, cut off the coat and scab, clamped the cotton ball with tweezers, dipped in enough liquid to wipe the affected part, and repeatedly rubbed it with several cotton balls for 3 or 4 times. After smearing, send the sick animal into the original cage, 5-7 days later, and then use the method to treat once, can be cured.

According to the data, foxes and raccoons with acariasis can rub the affected part with 2% trichlorfon or 15% concentrated iodine tincture for more than 2 times, which has a better therapeutic effect.

5.4 isolation treatment when mite disease occurs in foxes and raccoons, the whole group should be examined and the diseased animals should be quarantined and treated immediately. The contaminated cages are disinfected with 2%-3% thermocladiene or Lysol solution. It is best to thoroughly disinfect the cage and the environment with the above solution immediately after the treatment of sick animals, leaving no hidden danger. In order to prevent the spread of acariasis, the crusts and hairs cut off by the affected animals should be destroyed. When introducing new varieties, they should be strictly checked and kept in isolation for a period of time, and then reared in mixed groups when there is no acariasis. After contact with sick animals, breeders should pay attention to disinfection to avoid cross-infection.